For what it's worth.
Had a buddy that got blown out of a PT boat in '44, partly deaf, part blind, and limping, they 4F'ed him and he spent the latter part of the 1940's, early 1950'srecovering and shooting. Weren't any bullets to be had, and lead was in real short supply, so he started shooting "Kerksite" (not sure of the speelling...but it was a Zinc alloy sold for casters back then).
He gave me a few 45-70 gullets he'd been using, mostly un-shot, but some shot and recovered (they looked the same except for rifling marks). He did kill a bit of game with them, but it lacked the penetration of lead. He's not lube them at all, bare-naked shooting.
As he put it, they were, "Harder than the back of Moses' head."